Here's how much Canberra Catholic schools are over funded

Catholic schools in Canberra will receive well above their share of taxpayer dollars next year, with new data revealing the true extent of over-payment according to the federal government's new needs-based funding formula.

Federal Education Department figures show the system will receive 116.3 per cent of the school resourcing standard from the Commonwealth in 2018 - a figure that should be 80 per cent.

Per student funding has changed only slightly but a shift in how need is calculated has revealed the huge leap in the sector's share of the school resourcing standard.

The 116 per cent in over-funding does not include what the system will receive from the ACT government or an additional tens of millions of dollars promised to the Catholic Archdiocese of Canberra and Goulburn after its fury at projected cuts.

Australian Education Union ACT secretary Glenn Fowler said the new data, published under Freedom of Information laws at the union's request, showed the federal government's new needs-based funding model was "not about need [but] about the extension of privilege".

"We have arrived at the farcical situation where so-called private schools are more than fully funded from one level of government, and the rest of the money they get just gives them more swimming pools and bigger gates," he said.

"Nobody with any interest in equity could endorse this.

"Who ever said some kids are less important than others?"

ACT Catholic schools were traditionally funded to a socioeconomic score of 101 - the national average - instead of its actual average score of 116, which will be applied from next year.

The Catholic sector has long argued socioeconomic modelling disadvantages the ACT due to its unique demographic makeup.

Catholic Education Office director Ross Fox said the switch to receiving 116 per cent of the school resourcing standard in 2018 proved the government's calculation of need was flawed.

"All of a sudden we've gone from being under-funded to dramatically over-funded but the needs of school children at non-government schools in the ACT haven't changed at all," Mr Fox said.

"This information confirms the concerns of Catholic Education that this government has chosen to redefine the needs of students in Catholic schools in the ACT in a way that disadvantages them significantly."

Other over-funded schools within the ACT include Daramalan College (projected to receive 148.4 per cent of the school resourcing standard in 2018), Burgmann Anglican School (143.2 per cent), Brindabella Christian schools (129.7 per cent) and Orana Steiner School (115.8 per cent).

Each will transition to 80 per cent of the school resourcing standard over the next decade, with the federal government offering an additional $57.9 million to some ACT private schools to ease the cuts or slowing of funds.

An Education Department spokesperson said it was still unknown how that money would be distributed. Mr Fox said he understood the Catholic system would receive about $35 million.

Mr Fox said the Catholic Education Office would distribute its government funding according to its own calculation of need.

"It's absolutely based on the needs of students and the first need of every student is to have a qualified, well-trained, capable teacher in front of every classroom and then we look at the needs of individual students and what additional support they need," he said.

A federal Education Department spokesperson said the new school resourcing standard accounted for a school's socioeconomic score, provided more targeted funding for students with disability and made changes to capacity to contribute settings for primary schools.

"Schools that currently attract less than their new Commonwealth shares will transition to the higher shares within six years and schools that attract more than their new Commonwealth share will transition to the lower shares within 10 years," the spokesperson said.